package cn.eshore.bnet.bpm.dao.hibernate;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
import org.springframework.orm.ObjectRetrievalFailureException;
import org.springframework.orm.hibernate3.HibernateCallback;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;

import cn.eshore.bnet.bpm.dao.GenericDao;

/**
 * This class serves as the Base class for all other DAOs - namely to hold
 * common CRUD methods that they might all use. You should only need to extend
 * this class when your require custom CRUD logic.
 * <p>
 * To register this class in your Spring context file, use the following XML.
 * 
 * <pre>
 *      &lt;bean id=&quot;fooDao&quot; class=&quot;cn.eshore.bnet.bpm.dao.hibernate.GenericDaoHibernate&quot;&gt;
 *          &lt;constructor-arg value=&quot;cn.eshore.bnet.bpm.model.Foo&quot;/&gt;
 *          &lt;property name=&quot;sessionFactory&quot; ref=&quot;sessionFactory&quot;/&gt;
 *      &lt;/bean&gt;
 * </pre>
 * 
 * @author <a href="mailto:bwnoll@gmail.com">Bryan Noll</a>
 * @param <T>
 *            a type variable
 * @param <PK>
 *            the primary key for that type
 */
public class GenericDaoHibernate<T, PK extends Serializable> extends
        HibernateDaoSupport implements GenericDao<T, PK> {
    /**
     * Log variable for all child classes. Uses LogFactory.getLog(getClass())
     * from Commons Logging
     */
    protected final Log log = LogFactory.getLog(getClass());

    private Class<T> persistentClass;

    /**
     * Constructor that takes in a class to see which type of entity to persist
     * 
     * @param persistentClass
     *            the class type you'd like to persist
     */
    public GenericDaoHibernate(final Class<T> persistentClass) {
        this.persistentClass = persistentClass;
    }

    /**
     * {@inheritDoc}
     */
    @SuppressWarnings("unchecked")
    public List<T> getAll() {
        return super.getHibernateTemplate().loadAll(this.persistentClass);
    }

    /**
     * {@inheritDoc}
     */
    @SuppressWarnings("unchecked")
    public List<T> getAllDistinct() {
        Collection result = new LinkedHashSet(getAll());
        return new ArrayList(result);
    }

    /**
     * {@inheritDoc}
     */
    @SuppressWarnings("unchecked")
    public T get(PK id) {
        T entity = (T) super.getHibernateTemplate().get(
                this.persistentClass,
                id);

        if (entity == null) {
            log.warn("Uh oh, '" + this.persistentClass + "' object with id '"
                    + id + "' not found...");
            throw new ObjectRetrievalFailureException(this.persistentClass, id);
        }

        return entity;
    }

    /**
     * {@inheritDoc}
     */
    @SuppressWarnings("unchecked")
    public boolean exists(PK id) {
        T entity = (T) super.getHibernateTemplate().get(
                this.persistentClass,
                id);
        return entity != null;
    }

    /**
     * {@inheritDoc}
     */
    @SuppressWarnings("unchecked")
    public T save(T object) {
        return (T) super.getHibernateTemplate().merge(object);
    }

    /**
     * {@inheritDoc}
     */
    public void remove(PK id) {
        super.getHibernateTemplate().delete(this.get(id));
    }

    /**
     * {@inheritDoc}
     */
    @SuppressWarnings("unchecked")
    public List<T> findByNamedQuery(String queryName,
            Map<String, Object> queryParams) {
        String[] params = new String[queryParams.size()];
        Object[] values = new Object[queryParams.size()];
        int index = 0;
        Iterator<String> i = queryParams.keySet().iterator();
        while (i.hasNext()) {
            String key = i.next();
            params[index] = key;
            values[index++] = queryParams.get(key);
        }
        return getHibernateTemplate().findByNamedQueryAndNamedParam(
                queryName,
                params,
                values);
    }

    //
    // public List<T> findPageByProperty(String queryName,
    // Map<String, Object> queryParams, final int... rowStartIdxAndCount) {
    // getHibernateTemplate().setMaxResults(maxResults)
    // DetachedCriteria criteria = new DetachedCriteria();
    //
    // }

    public List findByNamedParam(final String queryString,
            final String[] paramNames, final Object[] values,
            final int firstResult, final int fetchSize) {

        if (paramNames.length != values.length) {
            throw new IllegalArgumentException(
                    "Length of paramNames array must match length of values array");
        }
        return (List) getHibernateTemplate().executeWithNativeSession(
                new HibernateCallback() {
                    public Object doInHibernate(Session session)
                            throws HibernateException {
                        Query queryObject = session.createQuery(queryString);
                        queryObject.setFirstResult(firstResult);
                        queryObject.setFetchSize(fetchSize);
                        if (values != null) {
                            for (int i = 0; i < values.length; i++) {
                                applyNamedParameterToQuery(
                                        queryObject,
                                        paramNames[i],
                                        values[i]);
                            }
                        }
                        return queryObject.list();
                    }
                });
    }

    /**
     * Apply the given name parameter to the given Query object.
     * 
     * @param queryObject
     *            the Query object
     * @param paramName
     *            the name of the parameter
     * @param value
     *            the value of the parameter
     * @throws HibernateException
     *             if thrown by the Query object
     */
    protected void applyNamedParameterToQuery(Query queryObject,
            String paramName, Object value) throws HibernateException {

        if (value instanceof Collection) {
            queryObject.setParameterList(paramName, (Collection) value);
        } else if (value instanceof Object[]) {
            queryObject.setParameterList(paramName, (Object[]) value);
        } else {
            queryObject.setParameter(paramName, value);
        }
    }

}
